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Thread: Carbs

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    Carbs

    Hello everybody,


    I have a few questions maybe someone can help me


    I installed one on my carburettor Solec C35 phh with 31 Venturi an open air filter. and changed the main jets to 125 But the vehicle is still running thin, thought goes to take 130 main jets I do not want to touch the air correction jet yet.
    As soon as the speed rises above 4500 rpm. Idle can be difficult to adjust but it works. Carburetor re-sealed with ultrasound cleaned and adapted to the intake manifold.


    Does anybody have experience with the jets in combination with open filters? (with the original filter running smoothly) and where can I get full radius air horns for the Solex? maybe even in different lengths to match the intake.


    Best regards Karl Heinz

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    Legendary Lancista 1,6 HF's Avatar
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    Re: Carbs

    Unless you're running on a track, do not run open trumpets. Adding foam 'socks' will protect the cylinders and also help with the 'lean' condition.
    Ed Levin
    Fulvia 1,6 HF

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    Legendary Lancista lancialulu's Avatar
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    Re: Carbs

    Quote Originally Posted by TBF-ZAK View Post
    Hello everybody,


    I have a few questions maybe someone can help me


    I installed one on my carburettor Solec C35 phh with 31 Venturi an open air filter. and changed the main jets to 125 But the vehicle is still running thin, thought goes to take 130 main jets I do not want to touch the air correction jet yet.
    As soon as the speed rises above 4500 rpm. Idle can be difficult to adjust but it works. Carburetor re-sealed with ultrasound cleaned and adapted to the intake manifold.


    Does anybody have experience with the jets in combination with open filters? (with the original filter running smoothly) and where can I get full radius air horns for the Solex? maybe even in different lengths to match the intake.


    Best regards Karl Heinz
    I am curious as to how you know the engine is running lean under load....

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    Re: Carbs

    Quote Originally Posted by lancialulu View Post
    I am curious as to how you know the engine is running lean under load....
    I have an afr meter inside so I see that he is running lean over 4500rpm. So in Frist Step i change the Main jet from 120 to 125.

    And i wear igt air Filter over the air horns

  5. #5
    Legendary Lancista lancialulu's Avatar
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    Re: Carbs

    Quote Originally Posted by TBF-ZAK View Post
    I have an afr meter inside so I see that he is running lean over 4500rpm. So in Frist Step i change the Main jet from 120 to 125.

    And i wear igt air Filter over the air horns
    Have you qualified this by running a hot engine for 5km at 4500 and stopping and looking at the plugs. Unless the spark plugs are white maybe you have a poor calibration....

    I run open trumpets (with socks) on 40Solex on a 1300. 34mm venturi and 150 main jet. Hot Var 1016 Cam and ported head and exhaust. No problems (except transition from idle circuit to main jet). I have no instrumentation other than how it drives and how the plugs look.

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    Legendary Lancista Marnix's Avatar
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    Re: Carbs

    The C.32 and C.35 will be rather difficult to run with open inlets. You may have noticed two brass small tubes sticking into the barrel at the air input side. That is to add fuel (make it richer) at a certain power level (Solex explains it differently: they say you can run leaner at cruise, because extra fuel is added when exceeding a certain power level by these tubes).
    The tubes opertate at a certain underpressure at the input side: when there is sufficient underpressure, fuel is sucted in through channels in the head (up, through the head, and down again).
    Now, this implies that you got sufficient underpressure when you go to high power. The underpressure comes from the velocity stacks (they MUST be the right ones to work correctly) and also the resiastance of the AIR FILTER.
    Conclusion: the C.32 and C.35 PHH are not really suitablme to be run with open trumphets (and of the wrong dimensions?) If you do, you will find the high power running too lean (because the extra fuel is not delivered by the small tubes). You will also find that the setting of idle is most difficult if you don't use the air filter (it is a bit more complex to explain that one).
    The C.42 DDHF (except the very early ones) can be run with open trumphets because they don't use this fuel enrichment setup like in the C.32 and C.35 PHH.
    Lancia Fulvia 2C 1964
    Lancia Fulvia Coupe Rallye 1,3 1968
    Porsche 924 1979
    Alfa Romeo 33 1.4IE 1993

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    Re: Carbs

    Quote Originally Posted by Marnix View Post
    The C.32 and C.35 will be rather difficult to run with open inlets. You may have noticed two brass small tubes sticking into the barrel at the air input side. That is to add fuel (make it richer) at a certain power level (Solex explains it differently: they say you can run leaner at cruise, because extra fuel is added when exceeding a certain power level by these tubes).
    The tubes opertate at a certain underpressure at the input side: when there is sufficient underpressure, fuel is sucted in through channels in the head (up, through the head, and down again).
    Now, this implies that you got sufficient underpressure when you go to high power. The underpressure comes from the velocity stacks (they MUST be the right ones to work correctly) and also the resiastance of the AIR FILTER.
    Conclusion: the C.32 and C.35 PHH are not really suitablme to be run with open trumphets (and of the wrong dimensions?) If you do, you will find the high power running too lean (because the extra fuel is not delivered by the small tubes). You will also find that the setting of idle is most difficult if you don't use the air filter (it is a bit more complex to explain that one).
    The C.42 DDHF (except the very early ones) can be run with open trumphets because they don't use this fuel enrichment setup like in the C.32 and C.35 PHH.
    is the resistance of the air filter itself sufficient? or is the factory airbox included in your statement about the idle setting?
    bmarler/
    1967 fulvia sport zagato
    1961 appia vignale convert.

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    Legendary Lancista Marnix's Avatar
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    Re: Carbs

    Quote Originally Posted by bmarler View Post
    is the resistance of the air filter itself sufficient? or is the factory airbox included in your statement about the idle setting?

    Ooops. I was assuming the full air box + filter. To be honest, never tried measuring the resisatnce of the filter and NOT using the air box...

    I am not saying you can't set idle right without the air box (some do, with flow metering at the velocity stacks); it is just more difficult…

    The statement about needing the right resistance to get additional fuel from the brass tubes remains. I am assuming Solex /Lancia did some calculations/experiements to have them start adding fuel at more or less the right power point considering the type of velocity input stacks and air box with air filter....

    It is aprox of course: the resistance of the air filter will change over time when getting dirty/ wearing out... It is kind of importaznt to clean out the filter element regurarly on the Fulvia.
    Lancia Fulvia 2C 1964
    Lancia Fulvia Coupe Rallye 1,3 1968
    Porsche 924 1979
    Alfa Romeo 33 1.4IE 1993

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    Re: Carbs

    Quote Originally Posted by Marnix View Post
    Ooops. I was assuming the full air box + filter. To be honest, never tried measuring the resisatnce of the filter and NOT using the air box...

    I am not saying you can't set idle right without the air box (some do, with flow metering at the velocity stacks); it is just more difficult…

    The statement about needing the right resistance to get additional fuel from the brass tubes remains. I am assuming Solex /Lancia did some calculations/experiements to have them start adding fuel at more or less the right power point considering the type of velocity input stacks and air box with air filter....

    It is aprox of course: the resistance of the air filter will change over time when getting dirty/ wearing out... It is kind of importaznt to clean out the filter element regurarly on the Fulvia.


    If I see that correctly, does not further enlargement of the Main Jet mean anything? because fuel can not be supplied through the pipes?
    That means a bigger Main Jet will not work? or do I have to work parrale with another correction jet?

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    Re: Carbs

    Quote Originally Posted by Marnix View Post
    Ooops. I was assuming the full air box + filter. To be honest, never tried measuring the resisatnce of the filter and NOT using the air box...

    I am not saying you can't set idle right without the air box (some do, with flow metering at the velocity stacks); it is just more difficult…

    The statement about needing the right resistance to get additional fuel from the brass tubes remains. I am assuming Solex /Lancia did some calculations/experiements to have them start adding fuel at more or less the right power point considering the type of velocity input stacks and air box with air filter....

    It is aprox of course: the resistance of the air filter will change over time when getting dirty/ wearing out... It is kind of importaznt to clean out the filter element regurarly on the Fulvia.

    I've found the following settings on the net for the Solex c35 so I'm on bigger main jets.
    But if I understand you correctly, there will be no more fuel due to the drilling. Is that correct?

    rom the original Solex S.p.a. Technical Bulletin, No. 65-A/June 1967, supplied by the Lancia Competition Department.
    ______________________
    1.2 HF (76 x 77 engine)
    Full air cleaner
    HF cams

    Solex C. 35 PHH (CR. 186)
    Choke 29
    Main Jet 115
    Air Corr Jet 160
    Idle jet 42.5
    ______________________
    1.2 HF Corsa (77 x 67 engine, 1247 cc)
    No Air Cleaner
    HF Cams

    Solex C. 35 PHH (HF Corsa, special velocity stacks, C. 23263)
    Choke 31
    Main Jet 125
    Air Corr Jet 145
    Idle jet 42.5
    ______________________
    1.3 Rallye Coupe and Sport (77 x 69.7 engine, 1298 cc)
    Full Air Cleaner
    Standard Cams

    Solex C. 35 PHH 2 (CR. 192)
    Choke 29
    Main Jet 120
    Air Corr Jet 190
    Idle jet 42.5
    _______________________
    1.3 HF (77 x 69.7 engine, 101 BHP)
    Full Air Cleaner
    HF Cams

    Solex C. 35 PHH 3 (CR. 193)
    Choke 31
    Main Jet 120
    Air Corr Jet 180
    Idle Jet 42.5
    _________________________
    1.3 HF Corsa (77 x 69.7 engine, 114 BHP)
    No Air Cleaner
    HF Cams

    Solex 35 PHH 3 (HF Corsa, special velocity stacks C. 23263)
    Choke 31
    Main Jet 125
    Air Corr Jet 145
    Idle jet 42.5

    _________________________

    From the original Solex S.p.A. Technical Bulletin No. 71/October 1967, supplied by the Lancia Competition Department
    ______________________________________
    1.3 HFR Variante 1014 (77 x 69.7 engine, 132 BHP)
    No Air Cleaner
    HF variante 1014

    Solex C. 40 DDHF (Special velocity stacks)
    Choke 34
    Main Jet 145
    Air Corr Jet 155
    Idle jet 50

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